Interstitial CT lymphography-guided localization of breast sentinel lymph node: preliminary results

Accurate localization of the breast sentinel lymph node (SLN) can be challenging as a minimally invasive approach to the treatment of early-stage breast cancer. We tested the potential capability of interstitial computed tomographic lymphography (CT-LG) using a conventional contrast agent (iopamidol) for SLN mapping.

In 14 female dogs, 0.5 and 1 mL of undiluted iopamidol was injected subcutaneously into the 2 skin areas overlying the mammary gland. Contiguous, 2 mm-thick multidetector helical CT images were obtained through the upper breast and axilla before, and for 60 minutes after, gentle massage at the injection site. Three-dimensional (3D) CT images were obtained from the postcontrast images showing the greatest SLN enhancement. This CT-LG with 2 mL of iopamidol was also evaluated in 5 human female volunteers.

The direct connection of SLN and lymphatic vessels draining from the injection sites in the animal models was clearly visualized, even with 0.5 mL of iopamidol. With this dose, the SLN attenuation was maximally enhanced, with a mean of 274 Hounsfield units (HU) on the first postcontrast images. The topographic 3D images provided the comprehensive anatomy of these lymphatic pathways. Of the 28 SLNs and 184 distant nodes visualized on CT images, all of the SLNs (100%) and 161 (87.5%) of the distant nodes could be resected at premortem and/or postmortem, with a good correlation in the locations and sizes with those on the CT images. The CT-LG effectively localized 5 SLNs with averaged maximum attenuation of 223 HU in the human volunteers, without any significant adverse effects.

Interstitial CT-LG using small volumes of iopamidol can sufficiently visualize breast lymphatic drainage and may have potential utility for breast SLN mapping.